Effects of dietary protein on whole-body protein turnover and endocrine function in young-adult and aging dogs
Thirty-six adult female Beagles averaging 2 (young-adult) or 8 (geriatric) yr of age were used to assess the effects of graded levels of dietary protein (16, 24, or 32%) on endocrine-controlled regulation of whole-body protein turnover. Rates of whole-body protein synthesis (WBPS) and whole-body protein degradation (WBPD) were estimated using orally administered 15N-glycine and total excreta collection. Although N balance was similar for all dogs, N flux through the metabolic pool increased linearly (P < 0.05) as protein intake increased. Rates of WBPS, WBPD, or the difference between them were not influenced by age (P > 0.10). A quadratic increase (P < 0.05) in WBPS and WBPD was observed in response to dietary protein. Serum insulin-like growth factor-I (IGF-I), IGF-I-binding protein 3, and total IGF-I-binding proteins were higher (P < 0.05) in geriatric dogs than in young-adult dogs regardless of protein intake. These results indicate that dietary protein in excess of 16% may not be required to maintain N balance in young-adult and aging dogs despite the linear increase in N flux through the metabolic pool. Furthermore, age-induced changes in endocrine functionality may differ between dogs and other species. ©2001 American Society of Animal Science. All rights reserved.
Publication Source (Journal or Book title)
Journal of Animal Science
Williams, C., Cummins, K., Hayek, M., & Davenport, G. (2001). Effects of dietary protein on whole-body protein turnover and endocrine function in young-adult and aging dogs. Journal of Animal Science, 79 (12), 3128-3136. https://doi.org/10.2527/2001.79123128x